The hydrophilicity of photocatalytic films and the activity of photocatalytic decomposition of organic pollutants were mutually promoted. When organic pollutants are adsorbed on the surface of the material, the surface hydrophilicity decreases, while the photocatalytic process can decompose organic pollutants. Water droplets are easy to spread to the clean surface, making the surface of the material return to the hydrophilic state.

Hydrophilic film

When the material is hydrophilic, its surface is easy to absorb water molecules and form hydroxyl radicals under the action of light, which is beneficial to the photocatalytic process. Anheden et al. (1996) conducted an in-depth study on the photocatalytic performance of TiO2 and other semiconductor materials. The mechanism was that the materials would produce E - and H + after light irradiation, and the photoinduced E - and oxygen molecules (O2) would interact to produce superoxide radical (·O2-). Photoinduced H + interacts with water to produce hydroxyl radical (·OH), and finally these two kinds of free radicals interact with pollutants to decompose it. In the process

The decomposition of medium organic pollutants can improve the surface hydrophilicity of the substrate. Meanwhile, H + can be combined with adsorbed water to increase the content of -OH on the surface of the material and further improve the surface hydrophilicity of the material (Ollis et al., 1991; Schwarz et al., 1997).

Then Guan (2005) synthesized TiO2 / SiO2 composite films to target pollutants degradation of acetate, further study of the photocatalytic activity of normal induced hydrophilic material and material, the results show that with the improvement of materials hydrophilic material for acetic acid degradation of performance is obviously improved, this is a result of the improvement of hydrophilic can result in material in the process of photoinduced surface hydroxyl content increased significantly, the ultimate improves the performance of the materials of photocatalytic decomposition of organic pollutants.